A number of networks are moving towards a connection-oriented arrangement. An example of a connection-oriented technology is Asynchronous Transfer Mode (ATM). Another example of a proposed technology that includes a connection-oriented (or channel based) capability is known as the Infiniband Architecture (IBA), described in the Infiniband Architecture Specification vol. 1, release 0.9, Mar. 31, 2000, authored by the Infiniband Trade Association. While connection-oriented technologies offer many advantages, in many instances it is desirable to maintain an interoperability between an existing connectionless technology and the connection-oriented technology. It is also desirable to maintain such interoperability, for example, when transitioning from a connectionless technology to a connection-oriented technology (or network) to allow existing software and components (e.g., legacy software) to be used. The Institute for Electrical and Electronics Engineers (IEEE) 802.3 Ethernet local area network (LAN) standard is an example of a common connectionless technology for a network.
Current approaches to provide LAN emulation over a connection-oriented network (such as ATM) have a number of disadvantages. One example is ATM LAN emulation, which is in a specification provided by the ATM forum for the coexistence of legacy LANs and ATM LANs, ATM forum, “LAN emulation over ATM specification” version 1.0, 1995. The ATM LAN emulation specification is discussed in William Stallings, “Data and Computer Communications,” pages 487-495, fifth edition, 1997.
As described in Stallings, the ATM LAN emulation specification proposes the use of a centralized LAN emulation service (LES) to perform basic LAN emulation services for nodes in a network, including: to set up connections and to map Media Access Control (MAC) addresses to ATM addresses. The LES also includes a broadcast and unknown server (BUS) service to provide broadcast/multicast of a packet to a plurality of nodes upon request from a client, and to provide a specialized protocol to allow nodes to learn ATM addresses of other nodes (i.e., by sending a LE_ARP_request message).
Currently, there are no existing 802.3 LAN emulation mechanisms in place for Infiniband fabrics. Moreover, there are a number of disadvantages of systems such as the ATM LAN emulation mentioned previously. First, by using a centralized LES service, the network is prone to a single point of failure. Furthermore, the ATM LAN emulation described above, requires a separate and specialized address resolution protocol (ARP) (which is not compatible with the legacy or existing LAN networks) in order to attain the ATM address of a node corresponding to the node's MAC or LAN address. Moreover, calls through the operating system kernel requiring multiple buffer copies of data is typically required in many such existing computer systems, which can burden a processor with substantial overhead.
The specialized name service and address resolution protocol maps Internet Protocol (IP) addresses to the mediums connection semantics. This method requires client software on each node and a centralized LAN emulation (LANE) server node that processes the ARPs, broadcast frames and multicast frames. Current LAN emulation architectures that map connection-oriented networks to 802.3 Ethernet generally map the connections to IP network addresses. This restricts the protocol to Transmission Control Protocol/Internet Protocol (TCP/IP) only. Further, in current systems, broadcasting in software over connection-oriented networks typically requires a buffer copy for each channel to send to all remote connected nodes. In addition, multicast traffic is not typically supported over existing connection-oriented networks.
Therefore, there is a need for an 802.3 LAN emulation mechanism for Infiniband fabrics that solves the above noted problems of current systems.